1. Field of the Invention
The present invention relates generally to an apparatus for preparing an insulation wire by an electrodeposition coating method. More particularly, it relates to an apparatus for coating a conductive material with a resin layer by electrophoresis using a water dispersion synthetic resin varnish or a water soluble synthetic resin varnish and then recovering a coagulant applied thereto for insuring ready film-formation of the resin layer.
The purpose of the invention is to increase the economical advantage of the apparatus and to attain a non-pollutive operation.
2. Description of the Prior Art
Heretofore, according to known methods of electrodeposition coating of insulation on a conductive material, a varnish resin layer is formed on the conductive material by an electrophoresis using a water dispersion synthetic resin varnish or a water soluble resin varnish and then applying a coagulant as a film forming auxiliary agent, so that an insulation coated film is formed by heat-curing. In the heat-curing step of the known method, the coagulant adhered on or contained in the film is vaporized as a gas. However, recovery of the coagulant has not been practically conducted. There is only a proposal to remove it by a combustion in the presence of a catalyst.
These conventional methods are disadvantageous from the viewpoint of product cost, material savings of starting materials and because the operation is pollutive by nature.
Presently, 2-6 times of a coagulant to the total weight of the film resin has been lost in the electrodeposition of a water dispersion synthetic resin varnish in forming an insulation film, especially in the preparation of an electric wire. When the wire running speed is increased, loss of the coagulant is increased. Accordingly, it is disadvantageous from the economical viewpoint.
Also, since the varnish is cured at high temperature for forming the film, the coagulant is vaporized as a toxic gas, thereby causing air pollution such that the prior methods are disadvantageous from the viewpoint that they are polluting the atmosphere.
FIG. 1 is a block diagram of a conventional apparatus wherein the elongate conductive material is run in the direction indicated by the arrow line A through an annealing bath 2, a pretreatment bath 3, an electrodeposition bath 4, a part 5 for applying a coagulant, a preliminary drying and curing furnace 6 and a final curing furnace 7. In such conventional apparatus, the elongate wire-like conductive material 1, to which an insulation coating is to be applied, is first passed through the annealing furnace 2 to improve the processability thereof, and then, it is passed through the pretreatment bath 3 to clean the surface of the conductive material. It then is passed through the electrodeposition bath 4, filled with a water dispersion synthetic resin varnish or a water soluble synthetic resin varnish, to electrodeposit a resin layer and then through the part 5 for applying a gaseous coagulant thereto. Then, it is passed through the preliminary drying furnace 6 to remove most of the volatile materials by heating, whereupon it is passed through the final drying and curing furnace 7 to complete the insulation film.
In this type apparatus, the coagulant is lost by vaporizing at the part 5 for applying the coagulant and in the preliminary drying furnace 6, whereby the economical advantage is lost and the pollutive characteristics of the operation is adversely affected.